A vehicle engine control unit controls the amount of fuel and injection timing, based on the input such as a crank angle sensor signal. Engine control belongs to an area where high-level real-time processing is required. In recent years, standardization of vehicle control software is processing mainly in Europe. One example is found in the OSEK-OS disclosed in OSEK/VDX Version, OSEK/VDX Operating System, which is the code for a real time operating system.
In the description of Japanese Patent Laid-open No. 2004-192541 and Japanese Patent Laid-open No. Hei 7 (1995)-40794, the software incorporated in the control unit is classified into an application program and an interface program. The interface program transfers the information of the input/output signal connected to a control unit over to the application program, and does not require a change of the application program in response to hardware modification.